WO2019233709A1

WO2019233709A1 - Method and device for determining at least one physiological parameter

Info

Publication number: WO2019233709A1
Application number: PCT/EP2019/062254
Authority: WO
Inventors: Gert Küchler
Original assignee: Kuechler Gert
Priority date: 2018-06-08
Filing date: 2019-05-14
Publication date: 2019-12-12
Also published as: DE102018209198B3; EP3801226A1

Abstract

The method is used to determine physiological parameters (P) of a patient. At a pulse measurement point on the arm of the patient: at least one pulse measurement signal (PM) of a pulse pressure wave, which propagates inside the blood vessels starting from the heart, is sensed continuously over a sensing period of at least one hour; an electrical heart measurement signal (EM) of electrical activity of the heart is sensed continuously over the sensing period; and an oscillometric or auscultatory cuff-based blood pressure measurement signal (MM) is sensed at specified points in time during the sensing period. Values for a first pulse wave propagation velocity (PWG1) and for a first blood pressure (BD1) are calculated continuously over the sensing period on the basis of the sensed pulse measurement signal (PM) and the sensed electrical heart measurement signal (EM), wherein the sensed cuff-based blood pressure measurement signal (MM) is used for calibration in the calculation of the values for the first blood pressure (BD1). The sensed pulse measurement signal (PM) is divided into a first pulse measurement signal portion (PM1) of a pulse pressure wave arriving directly from the heart, and into a second pulse measurement signal portion (PM2) of a reflected pulse pressure wave. Values for a second pulse wave propagation velocity (PWG2) are calculated continuously over the sensing period on the basis of the first and the second pulse measurement signal portions (PM1, PM2). The first and the second pulse wave propagation velocities (PWG1, PWG2) and the first blood pressure (BD1) are physiological parameters (P) that are continuously determined over the sensing period.

Description

Method and device for determining at least one physiological parameter

The present patent application claims the benefit of German Patent Application DE 10 2018 209 198.6, the contents of which are incorporated herein by reference.

The invention relates to methods and apparatus for determining at least one physiological parameter of a patient.

The detection of physiological parameters is common and widely used in medical technology today. An example of such a detection of a physiological parameter is the measurement of arterial blood pressure. Typically, the blood pressure measurement is carried out oscillometrically or as an option by means of an inflatable arm cuff and a pressure sensor functioning according to the rivac-cocci principle.

Another sphygmomanometer and the associated detection method are described in DE 10 2005 014 048 B4. The detection method is based on the evaluation of the Pulse Transit Time (PTT). The duration of the pulse wave is determined from the heart to the periphery, for example to one of the fingers, for each heartbeat. The start time of the transit time measurement is the R peak of the ECG and the end time is the point in time at which the signal at the periphery, for example, on the finger, in particular pho- toplethysmographisch or pulsoximetrisch detected pulse measurement signal has the maximum slope. From the thus determined running time, taking into account further parameters, such as, for example, body size, the pulse wave velocity

(= PWG) and the blood pressure is determined.

EP 3 071 098 B1 and DE 10 2014 225 483 B3 describe a further method and a further device for determining physiological parameters, such as blood pressure. A correction algorithm is provided for generating an improved pulse measurement signal, in which the influence of a reflected signal component of the pulse pressure wave is largely eliminated in order to be able to better recognize and evaluate relevant characteristics of the pulse measurement signal. DE 10 2015 012 351 A1 describes a device for measuring the pulse wave velocity. The measured value acquisition takes place at a single point. The pressure fluctuations of a near-surface artery are measured. A sensor records the first heart sound of an acoustic wave propagating at a high propagation velocity similar to that of a longitudinal sound wave in the water. The maximum power of the first heart sound is in the frequency range between 10 Hz and 300 Hz. In addition, the actual pulse wave is recorded, which is transmitted as elastic deformation of the vessel wall at a much lower Geschwin speed and at frequencies below 3 Hz. From the time delay between the detected first heart sound and the arrival time of the pulse wave, the pulse wave transit time, the pulse wave velocity and the blood pressure (systolic and diastolic) are calculated. In the evaluation, the mentioned frequency ranges are analyzed separately. The measurement can be done continuously.

In EP 2 491 856 A1, a device for detecting a cardiac wave pulse is described, wherein noise, which can be caused by a body movement, is removed from the measurement signal. At least two adaptive frequency filters are used here.

US 2013/0018272 A1 describes a device and a method for measuring the pulse wave velocity, whereby the influence of the hydrostatic pressure, which varies depending on the position of the patient during the measured value acquisition, is eliminated.

EP 2 074 942 A1 describes a method and a device for continuous non-invasive blood pressure detection. A pulse pressure wave parameter, such as the pulse wave propagation velocity, and cardiac output are measured. Based on the measured values and a model of the relevant part of the arterial tree, the blood pressure is determined using a prediction method.

An object of the invention is therefore to provide a method of the type described above with improved over the prior art properties.

To solve this problem, a method according to the features of patent claim 1 is given. In the method according to the invention is such, at the at least one pulse measurement signal of a pulse pressure wave propagating from the heart within the blood vessels at a pulse measuring point located on the patient's arm, continuously over a detection period of at least one hour, an electrical heart measuring signal of a cardiac current continuously over the detection period and an oszillometri cal or ascertaining cuff blood pressure measurement signal at certain times during the detection period. Values for a first pulse wave propagation velocity and for a first blood pressure are continuously determined over the detection time span on the basis of the detected pulse measurement signal and of the detected electrical heart measurement signal, wherein the detected cuff blood pressure measurement signal is used for the calibration in the determination of the values of the first blood pressure. The detected pulse measurement signal is divided into a first pulse measurement signal component of a pulse pressure wave arriving directly from the heart and a second pulse measurement signal component of a reflected pulse pressure wave. On the basis of the first and the second Pulsmesssignalanteils values for a second Pulswellenausbreitungsgeschwindigkeit be determined continuously over the detection period. The first and second pulse wave propagation velocities, as well as the first blood pressure, are continuously determined physiological parameters over the detection period.

A special feature of the method according to the invention lies in the detection period of at least one hour continuous determination of said physiological para meters. Continuous determination here means a determination in each - or at least substantially each - heartbeat. Such a determination may also be referred to or understood as a beat-to-beat determination. For the physiological parameters in question, the current value is thus advantageously present at any time. In particular, the detection period can last up to 12 hours, preferably up to 24 hours, and most preferably 48 hours. Even longer detection periods are possible in principle. In particular, the method for ambulatory long-term blood pressure monitoring (English: ambulatory blood pressure monitoring, abbreviated: ABPM), preferably before for ambulatory long-term blood pressure measurement with a detection period of 24 hours.

In the following, a central pulse wave propagation velocity is understood to mean that speed with which the pulse pressure wave is located in the inner region of the heart Blood vessels spreads. This near-heart area of the blood vessels is referred to here as "central". Accordingly, a central blood pressure which is likewise mentioned below is the blood pressure which is close to the heart.

Conversely, a peripheral pulse wave propagation velocity is understood as meaning the speed with which the pulse pressure wave propagates in the cardiac-external area of the blood vessels. This cardiac region of the blood vessels is referred to herein as "peripheral." Accordingly, the peripheral blood pressure of the heartfem, for example, on the extremities th, prevailing blood pressure.

In particular, the first pulse wave propagation velocity is a peripheral pulse wave propagation velocity, and the first blood pressure is, in particular, a peripheral blood pressure. In particular, the second pulse wave propagation velocity may be a central or peripheral pulse wave propagation velocity.

With the method according to the invention it is possible for the first time, e.g. Central and peripheral Wer te for the Pulswellenausbreitungsgeschwindigkeit and the blood pressure continuously, so in particular special heartbeat to heartbeat, over a longer period of at least a Stun de determine and make available for further evaluation. Comparable, continuous values could not be determined with the methods known hitherto.

When determining the continuous values for the first pulse wave propagation speed and the first blood pressure, in particular the method described in DE 10 2005 014 048 B4 can be used. It is here on the detected pulse measurement signal zurückgegrif fen. In particular, a first pulse pressure wave transit time (PTT), ie the time span required by the pulse pressure wave from the heart to the pulse measuring point on the arm, is determined on the basis of the detected electrical heart measurement signal and the detected pulse measurement signal. The first pulse pressure wave propagation time is in particular determined as a time interval between the so-called R wave in the electrical heart measurement signal and the time of the maximum increase in the pulse measurement signal. The first (in particular peripheral) blood pressure can be determined from the first pulse pressure wave transit time determined in this way and taking into account the at least approximately the length of the course of travel between the heart and the pulse measuring point could determine the first (in particular peripheral) pulse wave propagation speed by means of a quotient formation.

For detecting the cardiac electrical measurement signal, e.g. an ECG sensor can be used. The ECG sensor can be embodied in particular as an integral component of a measuring device or as a connectable separate structural unit. Preferably, it is at least partially embedded in an arm sleeve.

In the case of blood pressure, continuous values, in particular of the systolic and / or diastolic blood pressure (in each case centrally and peripherally) can be determined.

The consideration of the cuff blood pressure measurement signal acquired only temporarily, in particular at specific, preferably cyclical calibration instants, for calibration purposes when determining the continuous values of the blood pressure can be carried out, for example, according to the method described in DE 10 2005 014 048 B4. In particular, the times at which the cuff blood pressure measurement signal is detected are significantly longer apart than two consecutive heart beats, e.g. 30 minutes at night or 15 minutes during the day.

For the determination of the continuous values for the second pulse wave propagation velocity, the pulse signal can be divided into a first pulse signal signal component arriving from the heart and a second reflected pulse signal component, in particular by means of one of the methods known for this purpose, for example also by means of the method described in EP 3 071 098 B1 described method. For the best possible division into the two signal components, it is advantageous to use the pulse measuring point lying on the patient's arm. This pulse measurement on the arm has been found to be much better than this. a pulse measuring point located on a finger, as described in DE 10 2005 014 048 B4 and in EP 3 071 098 B 1 as being particularly preferred.

For the determination of the second pulse wave propagation velocity, reference is made to the first pulse measurement signal component arriving from the heart and the second reflected pulse signal signal component. In this case, a second pulse pressure wave transit time, which is particularly important preferably the time difference between the arrival of the pulse pressure wave coming directly from the heart at the pulse measuring point and the arrival of the reflected pulse pressure wave at the pulse measuring point. As a measure of the respective time of arrival in each case the time is used with maximum slope in the first and in the second Pulsmesssignalanteil. The second pulse wave propagation velocity can be determined from the second pulse pressure wave transit time thus determined with reference to the two pulse measurement signal components, taking into account the likewise at least approximately known length of the running distance between the pulse measurement point and the reflection point by means of a quotient formation. In this case, it may possibly also be taken into account that the pulse pressure wave covers a part of the distance, in particular the partial distance between the pulse measuring point and a refractive point located at the transition to the arterioles in the region of the fingers or the partial distance between the heart and one at the branching of the heart Abdominal aorta (= abdominal aorta) located in the region of the ilium (= ilium), passes twice. Optionally, on the basis of the second pulse pressure wave propagation time or the second pulse wave propagation velocity, a second blood pressure may additionally be determined, in which case it may also be, in particular, a central or peripheral blood pressure, comparable to the second pulse wave propagation velocity.

Advantageous embodiments of the method according to the invention will become apparent from the Merkma len the dependent of claim 1 claims.

An embodiment in which a peripheral pulse wave propagation velocity is determined as the second pulse wave propagation speed is favorable. In this constellation, the reflection point of the reflected pulse pressure wave is preferably at the outer end of a extremity, in particular at the transition to the arterioles in the region of the fingers of the arm where the pulse measuring point is located. Compared with the originating directly from the heart pulse pulse wave, the reflected pulse pressure wave also passes heartfemere outer preparation che of the blood vessel system, namely in particular the area between the patient's arm located on the pulse measuring point and the fingers. In this respect, the values of the second pulse wave propagation velocity, which have also been determined on the basis of the reflected pulse pressure wave, here relate more to the conditions in cardiac and thus peripheral regions. Alternatively, there is another favorable embodiment in which a central pulse wave propagation speed is determined as the second pulse wave propagation speed. In this constellation, the reflection point of the reflected pulse pressure wave is preferably located at the junction of the abdominal aorta in the region of the iliac bone. Compared with the originating directly from the heart original pulse pressure wave passes through the reflected pulse pressure wave Lich also located in the interior of the body areas of the blood vessel system, namely in particular the area between the heart and the branching of the abdominal aorta. In this respect, the values of the second pulse wave propagation velocity, which have also been determined on the basis of the reflected pulse pressure wave, here relate to conditions in blood vessel system areas which are more in the interior of the body and thus more central than the blood vessel system areas which the original pulse pressure wave has on its direct Passing from the heart to the heart rate monitor on the arm. In a constellation with a reflection point located in the abdominal cavity, the values of the second pulse wave propagation velocity are therefore of central importance.

Where the reflection point is depends on the individual case.

According to a further advantageous embodiment, a pair of measured values which form the values determined for a moving time and, in particular, associated with the pulse wave propagation velocity and the respective blood pressure, are converted into a standard value pair from a standard blood pressure value and the associated corrected value of the pulse wave propagation velocity , The values of the relevant Pulswel lenausbreitungsgeschwindigkeit and the relevant blood pressure of a pair of measured values are particularly based on measurements. They reflect the current conditions in the blood vessels of the patient. If a general statement is to be made about the condition of the blood vessels, such as about the aging state of the blood vessels, it is advantageous to use values under standardized conditions in order to be able to make better comparable statements. Thus, a statement about the aging state of the blood vessels can be derived from the pulse wave propagation velocity. It has been found that this statement is more precise if, instead of the value of the pulse-wave propagation velocity determined on the basis of a current measurement, which is assigned to the value of the blood pressure also determined on the basis of the current measurement, a corrected value of the pulse-wave propagation velocity is assigned to the standard blood pressure value is used. This corrected value of the pulse wave The rate of expansion and the standard blood pressure value form the standard value pair calculated from the pair of measured values. This favorable conversion of the value of the blood pressure associated with a measurement based on a measurement and based even on a measurement on the value of the pulse wave propagation velocity to a corrected value, which is associated with a standard blood pressure value is taken on its own, so in particular without reference to the continuous determination of the first and the second pulse wave propagation velocity and the first blood pressure, the subject of a separate invention. Advantageously, for the standard blood pressure value, a systolic blood pressure of 120 mmHg or a diastolic blood pressure of 80 mmHg is used. These are common blood pressure levels in healthy people.

According to a further advantageous embodiment, a body position of the patient is detected. As a result, the physiological parameters can be determined with greater accuracy, in particular taking into account the then changed hydrostatic conditions, and make better follow-up evaluations. The same applies to a further advantageous embodiment, in which a movement of the patient is detected. In particular, according to another advantageous embodiment, the cuff blood pressure measurement signal is detected again as a function of a detected change in the body position or a detected movement, and the cuff blood pressure measurement signal, which has been re-detected, is then used for the calibration. The renewal of the values used for the calibra tion thus takes place in particular not only at certain predetermined time intervals, but preferably also due to a detected changed behavior of the patient. Otherwise, as a result of the changed behavior of the patient, undetected new conditions which have not been taken into account until the next cyclical recalibration could corrupt the measurement results and / or the values determined therefrom. The cuff-blood pressure measurement signal, in particular also other measurement signals, can preferably be recorded over the entire acquisition period in order to be available for subsequent evaluation.

According to a further advantageous embodiment, the value of the blood pressure which is determined during a lying time in a bed (cf., the English term "time in bed", abbreviated to "TIB") is corrected taking into account a correction term describing a baroreceptor sensitivity. It was recognized that the baroreceptors located in the human blood vessel walls, while lying in bed, so in particular at night, have a different sensitivity, such as a different pressure sensitivity than at times when the patient is not in bed, is instead and active, especially during the day. This has the consequence that the values for the physiological parameters, in particular for the pulse wave propagation velocity and / or the blood pressure, which are determined while lying down in the bed, can have deviations and / or inaccuracies. It is therefore advantageous to take into account these baroreceptor sensitivity, which is changed during lying in bed, in the determination of the physiological parameters, in particular of the relevant blood pressure. This correction by taking into account the baroreceptor sensitivity is particularly advantageous in egg nem on the basis of a pulse wave transit time or based on a Pulswellenausbreitungsgeschwin speed determined blood pressure. This further improves the accuracy of the values determined in particular at night. This is important because it is precisely on the basis of nocturnal values, for example blood pressure, that important statements can be made about the patient's state of health. This favorable consideration of the baroreceptor sensitivity in the determination carried out while lying in bed physiological rule parameters, in particular the relevant blood pressure, and the associated preferred embodiments or developments are taken on their own, ie in particular without reference to the continuous determination of the first and the second pulse wave propagation speed and the first blood pressure, the subject of a separate invention. In particular, the correction of a determined during the time in bed value of the relevant blood pressure, taking into account the baroreceptor sensitivity according to the Formelbezie hung:

(HF, _{b -} HF _a ,)

^BD Cor ^{~ BD} Unco _rr ^BRS (1)

HF K, al, where BDu _nkon to be corrected and Bϋk _oh the corrected value of the affected blood pressure, HF _akt the current heart rate, HF _Kai the heart rate at the time of calibration and BRS the baroreceptor sensitivity. The latter is preferably determined on the basis of the values determined during the entire time in bed for the relevant blood pressure and for the heart rate. According to a favorable embodiment, the baroreceptor sensitivity is determined as a quotient multiplied by a baro constant, which is determined by dividing the arithmetic mean value determined over the entire time in bed of standard deviations of the determined blood pressure determined in the respective partial observation period by the partial arithmetic mean over the entire time determined in bed arithmetic mean value of determined during several partial observation periods standard deviations of the determined during each partial observation period heart rate is formed. Preferably, the determination of the baroreceptor sensitivity BRS according to the equation:

respectively. Where BD is the blood pressure, HF is the heart rate, C _{baro is} the Borr constant, T B is the time in bed, N is the number of beats during the partial viewing periods, _{TIB is} the arithmetic mean determined in bed TIB over the entire time of the relevant size and SD _N (...) is a standard deviation for the x trachtungszeitraum in the respective Teilbe determined with N heartbeats values of the respective size, in this case the relevant blood pressure or heart rate BD HF, according to the function:

is determined. Where n is a run index for the total of N heartbeats of the sub-observation period, and

denotes the arithmetic mean of the quantity x determined over the partial observation period with N heartbeats.

According to another advantageous embodiment, the baroreceptor sensitivity is determined as a multiplied by the Baro constant over the entire time in bed arithmetic mean of several quotients, each by dividing a Stan dardabweichung the determined during one of several Teilbetrachtungszeiträumen Subjective fenden blood pressure by a standard deviation during the same observation period. heart rate determined. Preferably and in particular as an alternative to equation (2), the determination of the baroreceptor sensitivity BRS can be determined according to the equation:

'SO _N (BD)'

BRS C (4)

ISD _N (HF)) TIB. Here again BD denotes the relevant blood pressure, HF the heart rate, C _bararo the Baro constant, TIB the time in bed, N the number of heartbeats during the partial periods of observation, ^ the arithmetic mean of the respective time determined in bed TIB Size and SD _N (...) the standard deviation according to equation (3).

According to another advantageous embodiment, the Baro constant C _{βaro has} a value from the range between 50 min ¹ and 200 min ¹ , in particular a value from the range between 75 min ¹ and 150 min ¹ , preferably a value from the range between 80 min ¹ and 120 min and most preferably a value of 100 min ¹ . According to a further advantageous embodiment, the number N of heartbeats during the partial viewing periods has a value in the range between 3 and 30, in particular a value in the range between 5 and 20, preferably a value in the range between 10 and 15, and most preferably a value of 12. These advantageous values for the Baro constant C _βaro and for the number N of heartbeats during the partial observation periods apply in particular to both equation (2) and equation (4).

According to a further advantageous embodiment, it is checked whether there is an artifact or an obviously erroneous value (= measurement error) among the values determined for the respective blood pressure and / or the heart frequency during the respective partial observation period. If such an artifact or measurement error exists, no associated standard deviation is determined for the relevant sub-observation period. The relevant partial observation period is then used in the calculation according to equation (2) for the respective size, ie either for the relevant blood pressure or for the heart rate, and in the calculation according to equation (4) not at all, ie neither for the relevant blood pressure still for the heart rate, in the calculation of baroreceptor sensitivity BRS on. As a result, the accuracy of the determined baroreceptor sensitivity BRS can be further increased before preferably.

According to a further advantageous embodiment, consecutive partial observation periods, if appropriate apart from occasional time gaps, which result from an artifactual or measurement error-related omission of individual partial examination periods, differ by one heartbeat from one another. Thus, the entire measurement period during bedtime is used very well to determine the baroreceptor sensitivity BRS relevant for this measurement period. In particular, the determination of the baroreceptor sensitivity BRS takes place subsequently, for example on the basis of (measurement) data recorded for the entire measurement period.

To solve the task concerning the device, a device according to the features of claim 12 is given. The device according to the invention has to be applied to an arm of the patient pulse sensor for a detection period of at least one hour continu ous acquisition of a pulse measurement signal of a pulse wave propagating from Her zen inside the blood vessels, wherein the patient's arm forms a pulse measuring point at the the acquisition of the pulse measurement signal is effected by an ECG sensor to be applied to the arm of the patient for continuous measurement of an electrical cardiac output at the pulse site, a blood pressure cuff to be applied to the arm of the patient for oscillometric or ascultatory detection of a cuff. Blood pressure measuring signal at the pulse measuring point at certain times during the detection period, and an evaluation unit. In this case, the evaluation unit is designed to continuously determine values for a first pulse wave propagation velocity and for a first blood pressure based on the detected pulse measurement signal and the detected electrical heart measurement signal, and in the determination of the values of the first blood pressure the detected cuff blood pressure measurement signal Calibration, and dividing the acquired pulse measurement signal into a first pulse measurement signal component of a pulse pressure wave arriving directly from the heart and into a second pulse measurement signal component of a reflected pulse pressure wave, and continuously obtaining values for a second pulse wave propagation velocity over the detection period using the first and second pulse measurement signal components. stuffs. The first and second pulse wave propagation velocities, as well as the first blood pressure, are continuously determined physiological parameters over the detection period.

The device according to the invention has substantially the same preferred embodiments as the method according to the invention. In addition, the device according to the invention and its preferred embodiments essentially offer the same advantages that have already been described in connection with the method according to the invention and its preferred embodiments.

In particular, the device can be embodied as a combined device, in which at least most of the components, such as preferably the pulse sensor, the ECG sensor, the blood pressure cuff and at least a part of the evaluation unit, which is designed in particular in several parts, as well as any further subcomponents, such as e.g. a body position sensor and / or a BEWE movement sensor, are combined to form a common unit. This preferred design is particularly space-saving and simplifies handling on the patient.

Further features, advantages and details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing. It shows:

1 shows an embodiment of a device applied to the arm of a patient measuring device for continuously noninvasive determination of physiological parameters of the patient at a location on the arm reflection point for the reflected pulse pressure wave,

2 is an enlarged and detailed representation of the measuring device according to FIG. 1,

3 is a block diagram with processing steps carried out in the measuring device according to FIG. 1 for determining the physiological parameters, FIG.

4 recorded or derived signal waveforms in the measuring device according to FIG. 1, FIG.

FIG. 5 shows the measuring device according to FIG. 1 applied to the arm of a patient at a reflection point for the reflected pulse pressure wave lying in the abdominal space, and FIG Fig. 6 is a stored in the meter of FIG. 1 characteristic field for describing the non-linear relationship between two determined in the meter physiological Pa parameters, namely between the pulse wave velocity and the blood pressure.

Corresponding parts are provided in FIGS. 1 to 6 with the same reference numerals. Also details of the embodiments explained in more detail below may constitute an invention in itself or be part of an inventive subject matter.

In Figs. 1 and 2 an embodiment of a device 1 for the continuous non-invasive detection of physiological parameters P of a patient 2 is shown. The device 1 is at a pulse measuring point 3 on the particular left arm of the patient create. It is out as a combined device leads and contains (see Fig. 2) an inflatable arm cuff 4, cuff pressure sensor 5, an ECG sensor 6 with at least two receiving electrodes 7 and 8, a pulse sensor 9 as an optional body position sensor 10 and a likewise optional motion sensor 11th and an evaluation unit 12. The sensors, so the cuff pressure sensor 5, the ECG sensor 6, the pulse sensor 9, the body position sensor 10 and the motion sensor 11 are at least partially embedded or integrated in the arm sleeve 4. They are each connected to the evaluation unit 12, which is also partially embedded or integrated in the arm sleeve 4 with a sleeve partial evaluation unit 28. In addition, the Auswertein unit 12 with an external Teilaus value unit 29 has a second component which is connected by means of a suitable, in particular also detachable data connection signal and / or data technology with the sleeve Teilauswerteeinheit 28.

The inflatable arm cuff 4 and the cuff pressure sensor 5 are components of a known blood pressure sensor, which detects the blood pressure BD oscillometric or askultatorisch. For this purpose, the arm sleeve 4 is inflated with air at certain times, in order thereafter to detect a cuff blood pressure signal MM when the air is released by means of the cuff pressure sensor 5. The pump for inflating the arm sleeve 4 and its drive unit are not shown in the figures for reasons of clarity. The pulse sensor 9 works in the embodiment shown after the reflection Prin zip. It has a green LED (not shown) that irradiates the patient's arm 2 with a green interrogation light signal, and a suitable light receiver (also not shown) that receives a response light signal reflected from the patient's arm 2. The answering light signal carries information to be evaluated on the pulse system 13 propagating in the vascular system of the patient 2, and thus also in the region of the arm at the pulse measuring point 3 detected by the green interrogation light signal. The pulse sensor 9 detects the pulse pressure wave passing by the pulse measuring point 3 13, which spreads from the heart 14 of the patient 2 within the blood vessels. The pulse sensor 9 is arranged in particular at the top, ie in the correctly applied state at the heart facing edge of the arm sleeve 4, to be able to detect the pulse pressure wave 13 even when the arm sleeve 4 is inflated.

The evaluation unit 12 optionally has display means 15, for example in the form of a display, and input means 16, for example in the form of input keys. By means of the input means 16, control commands or parameters, such as e.g. the height, weight and / or age of the patient 2 are entered. In addition, the evaluation unit 12 further components on which will be discussed in more detail. These other components of the Auswer teeinheit 12 need not necessarily be physically separated. They can also be implemented as subroutines of a software running on a signal or microprocessor in the evaluation unit 12 from running software. It is also possible that these other components are housed in a single unit or distributed to two or more units. In addition, the evaluation unit 12 and / or the device 1 at least one (not shown in detail ge) data interface, for example in the form of a corresponding socket, have.

In the following, the operation of the device 1 will be described with reference to the block diagram of FIG. 3 and the diagrams in Figs. 4 and 6.

The signals generated by the cuff pressure sensor 5, the body position sensor 10, the motion sensor 11, the ECG sensor 6 and the pulse sensor 9 are first ridden in a pre-processing unit 17. In addition to a possibly necessary selection and / or signal processing, in particular special digitization can be performed. The pre-processing unit 17 can either, as shown in Fig. 3, an input-side component of the evaluation unit 12, in particular the sleeve Teilauswerteeinheit 28, his. Alternatively, it may also be divided into a plurality of subunits which are assigned to the respective sensor and which, in a further alternative embodiment, are part of the respective sensor. In any case, after the treatment are a detected or generated by the cuff pressure sensor 5 cuff blood pressure measurement MM, detected by the body position sensor 10 body position measurement signal KM, detected by the motion sensor 11 or generated motion signal BM, detected by the ECG sensor 6 or. produced electrical heart signal EM of a heart current and a pulse detected by the pulse sensor 9 or pulse measurement signal PM before.

In particular, the pulse measurement signal PM, the cardiac electrical measurement signal EM, the body attitude measurement signal KM and the movement measurement signal BM are continuously measured over a detection period of e.g. Recorded 24 hours. By contrast, the cuff blood pressure measurement signal MM is not detected continuously, but only in preferably regular and in particular predeterminable time intervals, wherein in special situations an unscheduled detection can also take place. Typical time intervals between two scheduled acquisitions are 15, 30 or 60 minutes. All measurement signals PM, EM, KM, BM, and MM can be stored continuously over the entire detection period in the evaluation unit 12, in particular in the external Teilauswerteinheit 29 to subsequent To enable evaluations.

According to the lower diagram of FIG. 4, the detected pulse measurement signal PM is composed of a first pulse measurement signal component PM1 and a second pulse measurement signal component PM2. The first pulse measurement signal component PM1 shown in dashed lines in FIG. 4 is based on the detection of an original pulse pressure wave 18, which passes directly from the heart 14 at the pulse measurement point 3. The second Pulsmesssignalanteil PM2 shown in dash-dotted lines in Fig. 4 based on the detection of a reflected pulse pressure wave 19, which, for example and as shown in Fig. 1 schematically from the heart 14 coming to the end of the extremity, in the embodiment shown to the fingers, runs, where it is reflected at the transition to the arterioles and from this reflection point in the area of the fin ger coming past the pulse measuring point 3. The detected at the pulse measuring point 3 (com binierte) pulse pressure wave 13 contains as a part of the original pulse pressure wave 18 and as a further component of the reflected pulse pressure wave 19. Accordingly, the at the Pulse measuring 3 detectable and shown in solid lines in FIG. 4 pulse measurement signal PM a combined signal that is composed of a superposition of the first and second Pulsmesssignalanteils PM1, PM2. In Fig. 5, other conditions of reflection are shown. The detectable at the pulse measuring point 3 (again combined) pulse pressure wave 13 is composed of the coming directly from the heart 14 original pulse pressure wave 18 and a reflected pulse pressure wave 30, which results from a reflection in the abdomen together. The reflection point then lies in particular at the branching of the abdominal aorta in the area of the ilium. In any case, the pulse measuring point PM detectable at the pulse measuring point 3 has a superposition of two parts.

In a separation unit 20 of the evaluation unit 12, this superimposition is reversed ge and split the pulse measurement signal PM in the first and second Pulsmesssignalanteil PM1, PM2. This can be carried out, for example, according to the method described in EP 3 071 098 B1. Other distribution methods are also possible. In the Sig nalaufteilung can optionally also include the electrical heart signal EM with.

In a calculation unit 21 of the evaluation unit 12, different physiological parameters P, namely blood pressure values BD and pulse wave speeds PWG in various regions of the vascular system, are determined primarily on the basis of the pulse measurement signal PM and its two pulse measurement signal components PM1, PM2.

The procedure is based on the reproduced in Fig. 4 diagrams in which the signal waveforms of the electrical heart rate signal EM and the pulse measurement signal PM (including its two pulse measurement signal components PM1, PM2) are plotted over the time t, erläu tert. There are different pulse transit times (Pulse Transit Time = PTT) of the pulse pressure wave 13, preferably the original pulse pressure wave 18 and the reflected pulse pressure wave 19 and 30, respectively. The first pulse transit time PTT1 is the time difference between the time point of the so-called R wave in the electrical measurement signal EM and the time of the maximum gradient in the pulse measurement signal PM (or alternatively in the first pulse measurement signal component PM1, both supplies approximately the same result). It describes the duration of the original pulse pressure wave 18 from the heart 14 to the pulse measuring point 3 on the arm. Correspondingly, a further pulse-wave transit time, which is designated in greater detail in FIG. 4, can be determined on the basis of the time of the maximum slope in FIG second pulse measuring signal PM2 be determined. It describes the entire duration of the reflected pulse pressure wave 19 or 30 from the heart 14 to the measuring point 3. In addition, a second pulse wave transit time PTT2 is determined based on both Pulsmesssignalanteile PM1, PM2, which the entire duration of the heart 14 on the respective reflection point to the measuring point current reflected pulse pressure wave 19 and 30 minus the pulse transit time PTT1 of the heart 14 directly to the measuring point 3 ongoing original pulse pressure wave 18 represents. The second pulse wave transit time PTT2 can be determined as the time difference between the arrival of the pulse pressure wave 18 coming directly from the heart at the pulse measuring point 13 and the arrival of the reflected pulse pressure wave 19 or 30 at the pulse measuring point 13. In each case, the time with maximum gradient in the first and in the second pulse measurement signal component PM1, PM2 is used as a measure of the respective arrival time. The second pulse wave transit time PTT2 describes in the reflection ratios according to FIG. 1 the transit time of the pulse pressure wave 19 from the pulse measuring point 3 to the reflection point on the fingers and back to the pulse measuring point 3, ie peripheral conditions. On the other hand, in the case of the reflection ratios according to FIG. 5, the second pulse wave transit time PTT2 describes the transit time of the pulse pressure wave 30 from the heart 14 to the reflection site in the abdomen and back to the heart 14, ie central conditions.

From the first pulse transit time PTT1 thus determined, a first blood pressure BD1 is calculated in the calculation unit 21 by means of the functional relationship explained in DE 10 2005 014 048 B4, taking into account further parameters. In particular, a blood pressure calibration value BDKal determined from the cuff blood pressure measurement signal MM also flows into this calculation in each case in a calibration unit 22 of the evaluation unit. If, on the basis of the movement signal BM and / or on the basis of the body position measurement signal KM, it is detected that the patient 2 has significantly moved and / or has significantly changed his / her body position and, as a result, the hydrostatic conditions in the vascular system, the libration unit 22 is triggered causes an unscheduled calibration. For this purpose, if necessary, additional detection of a current cuff blood pressure measurement signal MM is initiated in order to determine therefrom a blood pressure calibration value BDKal adapted to the new conditions.

The above statements apply in particular to the determination of the systolic blood pressure. In the principle analogous determination of the diastolic blood pressure who used the other pulse wave transit times. For example, PTT1 becomes the first pulse wave transit time then, in particular, the time difference between the time of the minimum in the pulse measurement signal PM (or alternatively in the first pulse measurement signal component PM1, both in turn yields approximately the same result) and the time of one of the diastole corresponding spikes in the electrical measurement signal EM used.

In addition, in the calculation unit 21, a first and second pulse wave propagation speed PWG1 and PWG2 are calculated from the pulse-wave transit times PTT1, PTT2 taking into account the at least approximately known running distances. Optionally, a second blood pressure BD2 may be determined on the basis of the second pulse-wave transit time PTT2 or the second pulse-wave propagation velocity PWG2.

Thus, the first pulse wave propagation velocity PWG1 and the first blood pressure BD1 are determined in the calculation unit 21 on the basis of the pulse measurement signal PM (or alternatively based on the first pulse measurement signal component PM1) and the cardiac electrical measurement signal EM. On the other hand, the second pulse wave propagation velocity PWG2 (and the optional second blood pressure BD2) are determined in the calculation unit 21 based on both the first pulse measurement signal component PM1 and the second pulse measurement signal component PM2.

The blood pressure values BD1, BD2 and pulse wave propagation speeds PWG1, PWG2 determined in the calculation unit 21 from the pulse measurement signal PM and / or from the two pulse measurement signal components PM1, PM2 are advantageously continuously detected over the acquisition period, i. especially with every heartbeat. This physiological parameter P provides the device 1 preferably completely, so that the condition of the patient 2 very well documented and can be monitored.

Depending on the reflection ratios, the interpretation of the second pulse wave propagation speed PWG2 (and the optional second blood pressure BD2) differs.

In the reflection ratios according to FIG. 1 with the reflection point on the fingers, the second blood pressure BD2 and the second pulse wave propagation velocity PWG2 describe relationships in the peripheral area of the blood vessel system between the pulse measuring point 3 on the arm and the reflection point on the fingers. In this case, the second blood pressure BD2 is a peri- and the second pulse wave propagation velocity PWG2 is a peripheral pulse wave propagation velocity.

In the reflection ratios according to FIG. 5 with the reflection site in the abdominal cavity, the second blood pressure BD2 and the second pulse wave propagation velocity PWG2 describe relationships in the interior of the body and namely in the central region between the heart 14 and the abdominal reflection site. Accordingly, in this case, the second blood pressure BD2 is a central blood pressure and the second pulse wave propagation velocity PWG2 is a central pulse wave propagation velocity.

The first blood pressure BD1 and the first pulse wave propagation speed PWG1 always describe the relationships in the region between the heart 14 and the pulse measuring point 3 on the arm, ie in a rather peripheral region of the vascular system. These are always peripheral values.

The device 1 offers a second possibility for determining the central blood pressure ZBD, namely using the cuff blood pressure measuring signal MM. The latter is used in a further calculation unit 23 of the evaluation unit 12 for a known NPMA (N-points-moving-average). Algorithm subjected. The resulting value for the central blood pressure ZBD can in particular be compared with the value for the central blood pressure ZBD ascertained on the basis of the pulse measurement signal PM in the calculation unit 21. Deviations determined here can be used to adapt the calculations, for example to carry out a new calibration.

The relation stored in the calculation unit 21 between the blood pressure BD on the one hand and the pulse-wave transit time PTT or the pulse path propagation speed PWG linked directly thereto via the respective travel path is reproduced in the characteristic field according to FIG. In Fig. 6, the blood pressure BD is plotted against the Pulswellenausbrei processing speed PWG, wherein the coordinate axis contains no value data. The values of the pulse wave propagation speed PWG depend on the particular case. In particular, they move between 3 cm / ms and 20 cm / ms. In the calculation unit 21, the currently relevant characteristic curve 24 corresponding to the current one becomes from this characteristic field current blood pressure calibration value BDKal selected. In the Ausfüh approximately example shown in Fig. 6, this is the characteristic 24, which is highlighted by a thicker line thickness. With the currently valid characteristic curve 24 there is a clear association between the respective blood pressure BD1, BD2 and the respective pulse wave propagation speed PWG1, PWG2.

The values of the relevant pulse-wave propagation speed PWG1, PWG2 and of the respective blood pressure BD1, BD2 determined for a same point in time form a measured value pair 25, which is entered by way of example in FIG. The relevant Pulswellenausbrei tion speed PWG1, PWG2 is often used as a starting point for subsequent evaluations of the condition of the patient 2, for example, to determine the aging state of the vascular system. Since the value of the pulse wave propagation velocity PWG depends not only on the aging state of the vascular system of interest, but also on the current value of the blood pressure BD, the quality of the follow-up evaluations is reduced.

In order to avoid this and to reduce the influence of the dependence of the Pulswellenausbreitungsgeschwin speed PWG from randomly prevailing blood pressure BD in the follow-up evaluations, as completely as possible excluded, carried out in a correction unit 26 of the evaluation unit 12 is a conversion of the measured value pair 25 in a standard value pair 27 from a standard blood pressure value SBD and the associated corrected value of the pulse wave propagation speed PWG. The (systolic) standard blood pressure SBD is for example 120 mmHg. He is registered in the characteristic field of FIG. 6 as a dashed horizontal line. The conversion to the standard value pair 27 can be illustrated graphically using the characteristic field. Based on the measured value pair 25, the intersection with the horizontal line indicating the standard blood pressure value SBD is searched for on the same (currently valid) characteristic curve 24. This intersection specifies the default value pair 27. If the current characteristic curve 24 and the known standard blood pressure value SBD are known, a corrected value of the respective pulse wave propagation velocity KPWG1, KPWG2 can be determined on the basis of the unambiguous assignment. This corrected value then always applies to the same standard blood pressure value SBD, so that it leads to significantly better results in the subsequent evaluations. Correction unit 26 implements a further correction algorithm for the relevant blood pressure BD1, BD2. By means of this further correction algorithm, the negative influence of a change in the baroreceptor sensitivity at night on the accuracy of the determined respective blood pressure BD1, BD2 is largely eliminated. For this purpose, the relevant uncorrected blood pressure BD1, BD2 is corrected according to equation (1) already mentioned above and reproduced here again:

where BDu _nkon the corrected and Bϋk _oh the corrected value of the relevant blood pressure, HF _akt the current heart rate, HF _Kai the heart rate at calibration time and BRS baroreceptor sensitivity. In the notation of equation (1), the collection parameters BDu _nkon and BD _KOH respectively cover all two blood pressure values BD1, BD2 and corrected blood pressure values KBD1, KBD2 to be corrected. The current heart rate HF _akt and the heart rate at the calibration time HF _Kai can each be determined, for example, on the basis of the electrical heart measurement signal EM. Baroreceptor sensitivity BRS is calculated in accordance with one of the equations (2) and (4) explained in detail above prior to the description of the figures. The above statements are hereby incorporated by reference.

The corrected first and / or second pulse wave propagation velocities KPWG1, KPWG2 ascertained in the correction unit 26, as well as the corrected first and / or second blood pressure values KBD1, KBD2 at the output of the evaluation unit 12, are determined as continuously determined physiological parameters P, for example for a follow-up evaluation made available.

Claims

claims

1. A method for determining physiological parameters (P) of a patient (2), in which

a) at least one pulse measuring point (3) located on the arm of the patient (2):

a pulse measurement signal (PM) of a pulse pressure wave (13), which propagates from the heart (14) within the blood vessels, is detected continuously over a detection period of at least one hour,

- An electrical cardiac output signal (EM) of a cardiac current is detected continuously over the detection period, and

b) an oscillometric or ascertaining cuff blood pressure measuring signal (MM) is detected at specific points in time during the detection period; b) values for a first pulse wave propagation velocity continuously over the detection time span based on the detected pulse measurement signal (PM) and the detected electrical cardiac output signal (EM) (PWG1) and for a first blood pressure (BD1), wherein in the determination of the values of the first blood pressure (BD1), the detected cuff blood pressure measurement signal (MM) is used for calibration,

c) dividing the acquired pulse measurement signal (PM) into a first pulse measurement signal component (PM1) of a pulse pressure wave (18) arriving directly from the heart (14) and into a second pulse measurement signal component (PM2) of a reflected pulse pressure wave (19; and, based on the first and second pulse measurement signal components (PM1, PM2), values for a second pulse wave propagation velocity (PWG2) are determined continuously over the detection period, and

d) wherein the first and the second pulse wave propagation velocity (PWG1, PWG2) as well as the first blood pressure (BD1) over the detection time period are continuously determined physiological parameters (P).

2. Method according to claim 1, characterized in that a peripheral pulse wave propagation velocity is determined as the second pulse wave propagation speed (PWG2).

3. The method according to claim 1, characterized in that as a second Pulswellenausbrei- speed (PWG2) a central pulse wave propagation speed is ermit mined.

4. The method according to any one of the preceding claims, characterized in that a pair of measured values (25) which form the values of the pulse wave propagation velocity (PWG1; PWG2) and the blood pressure (BD1; BD2) determined at the same time are to be calculated into Default value pair (27) from a standard blood pressure value (SBD) and the associated corrected value of the pulse wave propagation velocity

(KPWG1; KPWG2).

5. The method according to claim 4, characterized in that as standard blood pressure value (SBD), a systolic blood pressure of 120 mmHg or a diastolic blood pressure of 80 mmHg is used.

6. The method according to any one of the preceding claims, characterized in that a body position of the patient (2) is detected.

7. The method according to any one of the preceding claims, characterized in that a movement of the patient (2) is detected.

8. The method according to any one of claims 6 and 7, characterized in that, depending on a detected change in the body position or a detected movement, the cuff blood pressure measurement signal (MM) is detected again, and the newly detected cuff blood pressure measurement signal (MM ) is then used for calibration.

9. Method according to one of the preceding claims, characterized in that the value of the relevant blood pressure (BD1, BD2) determined during a lying time in a bed is corrected taking into account a correction term describing a baroreceptor sensitivity.

10. The method according to claim 9, characterized in that the correction according to the formula relationship:

BDu _nkon to be corrected and Bϋk _oh the corrected value of the respective blood pressure (BD1; BD2), HF _akt the current heart rate, HF _Kai the heart rate at calibration time and BRS baroreceptor sensitivity be characterized.

11. The method according to claim 9 or 10, characterized in that the Barorezeptoren-

Sensitivity is determined on the basis of the values for the respective blood pressure (BD 1, BD2) and for the heart rate determined during the entire time in the bed.

12. Apparatus for determining physiological parameters (P) of a patient (2), comprising

a) a pulse sensor (9) to be applied to an arm of the patient (2) for continuously recording a pulse measurement signal (PM) of a pulse pressure wave (13) over a detection period of at least one hour, starting from the heart (14) within the blood vessels, whereby the arm of the patient (2) forms a pulse measuring point (3) at which the detection of the pulse measurement signal (PM) takes place,

b) an ECG sensor (6) to be applied to the arm of the patient (2) for continuous detection of an electrical cardiac output signal (EM) of a cardiac current at the pulse measuring point (3) over the acquisition period;

c) a blood pressure cuff (4) to be applied to the arm of the patient (2) for the oscillo- metric or ascultatory detection of a cuff blood pressure measurement signal (MM) at the pulse measuring point (3) at specific times during the detection period, and

d) an evaluation unit (12) which is designed

dl) based on the detected pulse measurement signal (PM) and the detected electrical heart measurement signal (EM) continuously over the detection time period values for a first pulse wave propagation velocity (PWG1) and for a first blood pressure (BD1), and in determining the values of the first blood pressure (BD1) to use the detected cuff blood pressure measurement signal (MM) for calibration, and

d2) dividing the acquired pulse measurement signal (PM) into a first pulse measurement signal component (PM1) of a pulse pressure wave (18) arriving directly from the heart (14) and into a second pulse measurement signal component (PM2) of a reflected pulse pressure wave (19; 30); the second pulse measurement signal component (PM1, PM2) continuously to determine values for a second pulse wave propagation velocity (PWG2) over the acquisition time period;

in which

e) the first and second pulse wave propagation velocities (PWG1, PWG2) and the first blood pressure (BD1) over the detection period are continuously determined physiological parameters (P).

13. Apparatus according to claim 12, characterized in that the second Pulswellenausbrei processing speed (PWG2) is a peripheral pulse wave propagation speed.

14. Apparatus according to claim 12, characterized in that the second Pulswellenausbrei processing speed (PWG2) is a central pulse wave propagation speed.

15. Device according to one of claims 12 to 14, characterized in that the Auswer teeinheit (12) is adapted to a measured value pair (25), the point for the same time determined values of the pulse wave propagation velocity (PWG1, PWG2) and the blood pressure (BD1; BD2), to be converted into a standard value pair (27) from a standard blood pressure value (SBD) and the corresponding corrected value of the pulse wave propagation velocity (KPWG1; KPWG2).

16. Apparatus according to claim 15, characterized in that the standard blood pressure value (SBD) is a systolic blood pressure of 120 mmHg or a diastolic blood pressure of 80 mmHg.

17. Device according to one of claims 12 to 16, characterized in that a Körperlage- sensor (10) is present, which detects a body position of the patient (2).

18. Device according to one of claims 12 to 17, characterized in that a movement sensor (11) is present, which detects a movement of the patient (2).

19. Apparatus according to claim 17 or 18, characterized in that the evaluation unit (12) is adapted to detect in response to a detected change in body position or a detected movement, the cuff blood pressure measurement signal (MM) again, and the re-detected cuffs Blood pressure measurement signal (MM) from then to use for calibration.

20. Device according to one of claims 12 to 19, characterized in that the Auswer teeinheit (12) is adapted to the determined during a lying time in a bed value of the respective blood pressure (BD1, BD2), taking into account a baroreceptor sensitivity descriptive To correct correction terms.

21. Apparatus according to claim 20, characterized in that the evaluation unit (12) is adapted to the correction according to the formula relationship:

perform, with BDU _nkon to be corrected and Bϋk _oh the corrected value of the relevant blood pressure (BD1, BD2), HF _akt the current heart rate, HF _Kai the heart rate time of calibration and BRS the baroreceptors sensitivity designated net.

22. Apparatus according to claim 20 or 21, characterized in that the evaluation unit (12) is adapted to the baroreceptor sensitivity based on the determined during the entire time in bed values for the respective blood pressure (BD1, BD2) and for the heart rate to determine.